Graphene lens structures for use with light engine and grid laser structures

ABSTRACT

Disclosed herein are various embodiments for laser arrays that include graphene lens structures located on laser-emitting semiconductor structures. In an example embodiment, an apparatus comprising (1) a laser-emitting epitaxial structure having a front and a back, wherein the laser-emitting epitaxial structure is back-emitting, and (2) a graphene lens structure located on the back of the laser-emitting epitaxial structure. Photolithography processes can be used to deploy the graphene lens structures on the laser structures.

CROSS REFERENCE AND PRIORITY CLAIM TO RELATED PATENT APPLICATION

This patent application claims priority to U.S. provisional patentapplication Ser. No. 62/520,868, filed Jun. 16, 2017, the entiredisclosure of which is incorporated herein by reference.

INTRODUCTION

This invention relates to semiconductors, and more specifically to thestructure of optical components of semiconductor lasers.

Laser arrays are becoming important in the field of communications, freespace optics (FSO), light detection and ranging (LiDaR), and materialsprocessing because of their higher operational optical power and highfrequency operation as compared to single lasers, fiber lasers, diodepumped solid state (DPSS) lasers, and light emitting diodes (LEDs).

Multi-conductive grid-forming laser structures are described in theinventor's previous work, US Pat. App. Pub. 2017/0033535, the entiredisclosure of which is incorporated herein by reference. As an exampleembodiment, this patent application describes a single unit ofsemiconductor lasers in a mesa structure, and their connections to ahigh speed electrical waveguide for high frequency operation. Each unitincorporates multiple emitters with multiple lenses. However, with theuse of a single device, the power and range of the lasers are limited.As an improvement on such technology, the inventor discloses a highperformance optical lens structure for use in combination with suchlaser structures. Moreover, a unique 2D material and process can be usedto form such lens structures on laser structures such as the LightEngine and Light Grid previously developed by the inventor. Thistechnology advancement as applied to semiconductor lasers and othersources like LEDs and the like and will lower the cost of new photonicstechnology while improving optical performance.

In an example embodiment, the inventor discloses an apparatus comprising(1) a laser-emitting epitaxial structure having a front and a back,wherein the laser-emitting epitaxial structure is back-emitting, and (2)a graphene lens structure located on the back of the laser-emittingepitaxial structure. The emitter structures, when used in an array,would have higher power density and greater potential for function whilethe new formation of lens formed on the back of the wafer allows highdensity optical components to be formed using simple photolithographicprocess.

In another example embodiment, a method for manufacturing the units canemploy photolithography techniques. For example, the method ofmanufacturing can comprise steps of (1) depositing graphene on a back ofa back-emitting multi-conductive grid-forming laser structure, (2)masking areas of the deposited graphene via photolithography, and (3)forming a graphene lens structure for the back-emitting multi-conductivegrid-forming laser structure by plasma etching the deposited graphene sothat the masked areas are not plasma etched.

This innovative process can use the unique high contrast index ofrefraction difference between the two materials graphene and asemiconductor such as GaAs to index guide or direct the light.

These and other features and advantages of the present invention will bedescribed hereinafter to those having ordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 show various views of an example top-emitting implantembodiment.

FIG. 6 shows a view of an example bottom-emitting implant embodiment.

FIGS. 7 and 7A-7C show views of an example top-emitting oxidationembodiment.

FIGS. 8-14 c show various views of an example bottom-emitting oxidationembodiment.

FIG. 15 shows a view of an example microstrip embodiment.

FIG. 16 shows a view of an example phase coherent embodiment.

FIG. 17 shows a view of an example embodiment that employs diffractiveoptical elements.

FIG. 18 shows a view of an example embodiment that employs patterndiffractive grating.

FIG. 19 shows a view of an example microlens embodiment.

FIG. 20 shows a view of an example tenth embodiment.

FIG. 21 shows a view of an example eleventh embodiment.

FIG. 22 shows a view of an example twelfth embodiment.

FIG. 23 shows an example of an additional pattern for a lasing grid withrespect to various embodiments.

FIG. 24 comparatively shows current flow as between an exampleembodiment designed as described herein and that taught by US Pat App.Pub. 2011/0176567.

FIG. 25 shows a cross-sectional view of an example laser apparatus thatincludes a laser structure in combination with a graphene lensstructure.

FIG. 26 discloses an example process that can be used to form thegraphene lens structure.

FIG. 27 shows an example where the graphene lens structure can bedesigned to vary in terms of width and spacing.

FIG. 28 shows an example graphene lens design that can replace theformed lens in extended cavity designs for the laser structure.

FIG. 29 shows an example graphene lens design that can replace adiffractive optical element (DOE) in the laser structure.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

FIG. 25 shows a cross-sectional view of an example laser apparatus 2500that includes a laser structure 2502 in combination with a lensstructure such as a graphene lens structure 2502. The laser structure2502 can be a laser-emitting epitaxial structure having a front 2504 anda back 2506, wherein the laser-emitting epitaxial structure isback-emitting. As shown by FIG. 25, the graphene lens structure 2502 islocated on the back 2506 of the laser structure 2502. The graphene lensstructure 2502 can be a single graphene lens structure or an array ofgraphene lens structures.

An example of a device that can be used as laser structure 2502 isdisclosed and described in the above-referenced and incorporated US Pat.App. Pub. 2017/0033535, a copy of which is included herewith as AppendixA. Additional examples of devices that can be used as laser structure2502 are disclosed and described in the following U.S. patents andpatent applications, the entire disclosures of each of which areincorporated herein by reference: (1) U.S. Pat. No. 8,848,757, (2) U.S.Pat. No. 7,949,024, (3) U.S. Pat. No. 8,520,713, (4) U.S. Pat. No.8,613,536, (5) U.S. Pat. No. 8,879,338, (6) U.S. patent application62/456,476, filed Feb. 2, 2017, and entitled “Methods to Advance LightGrid Structures for Low-Cost Laser Sources”, (7) U.S. patent application62/456,489, filed Feb. 2, 2017, and entitled “Fabrication of Light GridStructures with Wafer Scale Processing”, (8) U.S. patent application62/456,501, filed Feb. 2, 2017, and entitled “High Power Laser GridStructure for Applications over Distance”, (9) U.S. patent application62/456,518, filed Feb. 2, 2017, and entitled “Methods for Advancing HighBrightness Diodes”, and (10) U.S. patent application 62/459,061, filedFeb. 15, 2017, and entitled “Rigid Lasing Grid Structure ArrayConfigured to Scan, Communicate, and Process Materials Using DeformableLight Fields”.

FIG. 26 discloses an example process that can be used to form thegraphene lens structure 2502. At step 2600, graphene is deposited on theback 2506 of the laser structure 2502 (e.g., a back-emittingmulti-conductive grid-forming laser structure such as examples describedbelow in Appendix A). At step 2602, photolithography is used to maskareas of the deposited graphene. These masked areas will not be plasmaetched. FIGS. 27-29 show examples of mask patterns that can be used asthis step. Then, at step 2604, the graphene lens structure 2502 isformed by plasma etching the deposited graphene so that the masked areasare not plasma etched. As an example, O2 plasma etching can beperformed. This yields a photolithographic lens structure that can beused as the graphene lens structure 2502 in apparatus 2500. Thisinnovative process uses the unique high contrast index of refractiondifference between the two materials graphene and a semiconductor suchas GaAs to index guide or direct the light formed by the laser structure2500.

FIG. 27 shows an example where the graphene lens structure 2700 can bedesigned to vary in terms of width and spacing. In this example, thegraphene lens structure 2700 comprises a plurality of concentricgraphene rings 2702. The width of the graphene rings 2702 and thespacing between the graphene rings 2702 can be controlled and definedduring the masking process to achieve a desired optical effect for thegraphene lens structure 2700. Also, the example of FIG. 27 shows anexample 4×4 matrix mask for a unique array of 16 lenses—where 2 maskscan be employed for a light field and a dark field.

FIG. 28 shows an example graphene lens design that can replace theformed lens in extended cavity designs for the laser structure 2500. Theupper part of FIG. 28 shows different examples of width and spacingproperties that can be used for the graphene lens structure, and thelower part of FIG. 28 shows the example VCSEL laser structurecorresponding to FIG. 21 of Appendix A. The graphene lens structure canreplace the formed lens described in Appendix A in connection with FIG.21 to improve the design. Furthermore, a reflective coating can bedeposited over a surface of the graphene lens structure(s).

FIG. 29 shows an example graphene lens design that can replace adiffractive optical element (DOE) in the laser structure 2500. The upperpart of FIG. 29 shows different examples of width and spacing propertiesthat can be used for the graphene lens structure, and the lower part ofFIG. 29 shows an example laser structure corresponding to FIG. 18 ofAppendix A (see also the above-referenced and incorporated 62/456,476,62/456,489, 62/456,501, 62/456,518, and 62/459,061 patent applications).The graphene lens structure can replace the DOE described in variousembodiments of Appendix A to improve the design. As shown by FIG. 29,the graphene lens structure can be used with the laser structure todirect the laser light in a manner that makes the laser light appear asif originating from a single source.

While the present invention has been described above in relation toexample embodiments, various modifications may be made thereto thatstill fall within the invention's scope, as would be recognized by thoseof ordinary skill in the art. Such modifications to the invention willbe recognizable upon review of the teachings herein. As such, the fullscope of the present invention is to be defined solely by the appendedclaims and their legal equivalents.

APPENDIX A—US PAT APP PUB 2017/0033535

Laser arrays are becoming important in the field of communications,light detection and ranging (LiDaR), and materials processing because oftheir higher operational optical power and high frequency operation ascompared to single lasers, fiber lasers, diode pumped solid state (DPSS)lasers, and light emitting diodes (LEDs).

Laser arrays are commonly used in printing and communications, but inconfigurations which have a single separate connection to each laserdevice in the array for parallel communication where each laser couldhave a separate signal because it had a separate contact from the otherdevices in the array.

When array elements were tied together and driven with a single signal,the structures had too much capacitance or inductance. This highcapacitance/inductance characteristic slowed the frequency response forthe laser array down, thereby making such laser arrays slower as theyadded more elements. This is evidenced in the referenced works byYoshikawa et al., “High Power VCSEL Devices for Free Space OpticalCommunications”, Proc. of Electronic Components and TechnologyConference, 2005, pp. 1353-58 Vol. 2, and U.S. Pat. No. 5,978,408.

High speed laser arrays based on multi-mesa structures are described inthe inventor's previous work, US Pat App. Pub. 2011/0176567. US Pat App.Pub. 2011/0176567 describes a multi-mesa array of semiconductor lasersand their connections to a high speed electrical waveguide for highfrequency operation. However, the multi-mesa structures described in USPat App. Pub. 2011/0176567 suffers from a number of shortcomings.

One problem with mesa structures as described in US Pat App. Pub.2011/0176567 is they are typically brittle. This is a problem if thereis any mechanical procedure to bond to or touch the laser after the mesais formed. The mesas structures can be as small as 5 to 10 microns indiameter and consist of an extremely fragile material such as GaAs orAlGas, or other similar crystalline materials. These mesas must bebonded after processing and pressure is applied under heat so that thesubmount and the tops of the laser mesas are bonded electrically withsolder. When bonding an array of back emitting devices a typical failuremechanism at bonding is a cracked mesa which renders the laser uselessand can cause a rejection of the entire device. If there are 30 laserson the chip and after bonding 2 are broken, those 2 devices will notlight up. The testing still must be done causing an expensive process toremove failures.

Another problem is that the multi-mesa structure yields relatively lowlasing power as a function of chip real estate because of spacingrequirements for the multiple mesas that are present on the laser chip.

Another problem with the multiple mesa arrays produced by mesa isolationis that the lasers are separated by a distance which limits the overallsize of the array due to frequency response-dependent design parametersthat prefer shorter distance for a signal to travel across a contactpad. Later, arrays were used with elements which add in power such asthe multi Vertical Cavity Surface Emitting Laser (VCSEL) arrays whichwere used for infrared (IR) illumination. However these IR sources didnot support high frequency operation, so their pulse width was limitedto illumination instead of LIDAR, which needs fast pulse widths.

In an effort to satisfy needs in the art for stronger and more powerfulhigh speed laser arrays, the inventor discloses a number of inventiveembodiments herein. For example, embodiments of the invention describedbelow incorporate a high frequency electrical waveguide to connectlasers of the array together while reducing capacitance by forming thesignal pad on the substrate which employs the electrical waveguide.Embodiments of the invention also comprise the use of multi-conductivecurrent confinement techniques in a single structure to produce multipleareas that are conducting compared to non-conducting part of thestructures. The conducting parts form lasing areas or grids of lasingforming lasers without etching around the entire structure of the lasingpoint. Unlike the design described in the above-referenced U.S. Pat. No.5,978,408, embodiments of the invention disclosed herein are designedand processed so that the laser array is integrated with a high speedelectrical waveguide to enable high frequency operation. Embodiments ofthe present invention support new and unique opportunities in the designof a high power high speed light sources by exhibiting both highfrequency operation and a rigid structure, thus enhancing performanceand reliability over other designs known in the art.

In an example embodiment disclosed herein, a unique structure processedfrom a Vertical Cavity Surface Emitting Laser (VCSEL) epitaxial materialforms a grid of laser points from a single rigid structure which isconducive to high speed operation by reducing capacitance, increasingstructural integrity, and decreasing the fill factor as compared to thetypical mesa structures formed in VCSEL arrays such as those mentionedin US Pat App. Pub. 2011/0176567. It should be understood that the VCSELembodiment is only an example, and such a design can work with otherlaser types, such as Resonant Cavity Light Emitting Diodes (RCLEDs),LEDs, or Vertical Extended (or External) Cavity Surface Emitting Lasers(VECSELs).

The single contiguous structure described herein forms areas ofelectrical isolation of apertures using implanting of ions or areas ofnonconductive oxidation through microstructures or holes while keepingthe structural integrity of the material that is typically etched away.The formation of the new structure also allows a high speed signal to bedistributed between the different isolated laser conduction points orgrid. All of the P-contact areas of the laser grid can be connected inparallel to the signal portion of a ground-signal-ground (GSG)integrated electrical waveguide. The signal or current being switched onand off in the waveguide is distributed between all of the conductivepaths which form lasers. It should be understood that other types ofelectrical waveguides could be used such as a micro-strip waveguide.

The single contiguous structure has other benefits such as a larger basefor heat distribution within a larger plating structure. The lasing gridis closer together than the array structures to each other. The fartherthe lasers are apart the slower the frequency response or the speedwhich limits the ultimate bandwidth of the device due to the distancethe signal must travel to every single point in an array.

Accordingly, examples of advantages that arise from embodiments of theinvention include:

1. Rigid structure has a higher reliability in the chip bonding process

2. Rigid structure has a higher fill factor possibility

3. Rigid structure has higher reliability metal contacts

4. Rigid structure is simpler to process

5. Rigid structure has shorter distance between contacts enabling higherfrequency high power beams

6. Rigid structure is a better surface topology for a single lens orlens array to be attached

7. Rigid mesa structure produces another area for leads and contactswhich offer separation from potentials lowering capacitance.

8. Rigid structures allow higher integration with sub mounts because ofthe 3D nature of the contacts.

Furthermore, with an example embodiment, a laser grid is formed by morethan one lasing area enabled by confining the current to isolatedregions in the structure where conductivity exists as compared to thenonconductive ion implanted areas. The conductive and nonconductiveareas form a grid of light which has a single metal contact on thesingle solid structure for the active Positive contact and a single NContact on the surrounding ground structure which is shorted to the Ncontact area at the bottom of the trench isolating the two areas. By wayof example, FIG. 7C shows how an opening in the frame would helpincrease the speed.

These P and N contacts are then bonded to a high speed electricalcontact The 2 substrate and laser chips are aligned by a bonder thenheat and pressure are applied to bond the solder that has been depositedon one chip or the other. The high speed is enabled because the p pad isseparated from the n wafer ground by plating and solder heights butmostly by removing it off the laser substrate and placing it on anelectrical waveguide substrate. The physical separations dramaticallyreduces capacitance increasing the frequency response which is limitedby the capacitance of the circuit. This enables the lasing grid toachieve high frequency operation.

A single lens formed on the back of the substrate or a single Lensattached or bonded to the back of the grid structure could direct eachlasing point from a convergence point or to a convergence point. This isideal in collimating the beam output as if it were from a single source.

These and other features and advantages of the present invention will bedescribed hereinafter to those having ordinary skill in the art.

Embodiment 1 for US Pat App Pub 2017/0033535—Top-Emitting Implant

FIG. 1 shows an example of a first embodiment of the invention. In thisexample, a single solid structure is isolated from a surrounding groundwith an etch, and where the single solid structure has within it ionimplants. The ion implants create areas of the semiconductor materialthat are non-conductive, and these areas of non-conductivity forcecurrent flow through the lasing areas 2. Thus, the ion implants form alaser grid of multiple lasing areas 2 where current is confined toisolated regions in the structure where conductivity exists as comparedto the nonconductive ion-implanted areas. The conductive andnonconductive areas form a grid of light which has a single metalcontact on the single solid structure for the active positive (P)contact and a single negative (N) contact on the surrounding groundstructure which is shorted to the N contact area at the bottom of thetrench isolating the two areas or to negative metal on the surroundingground structure which is shorted to the N contact area at the bottom ofthe trench isolating the two areas (as in, for example, FIG. 7C (seereference numbers 781 and 782). These P and N contacts are then bondedto a high speed electrical contact, thereby enabling the lasing grid toachieve high frequency operation.

While FIG. 1 shows the lasing areas 2 arranged in a grid pattern, itshould be understood that many shapes and patterns of lasing areas 2could be formed. This allows many forms of structures withshapes/patterns of lasing areas 2 such as a honeycomb structure pattern(see, for example, FIG. 23 which illustrates another pattern which isone of many allowing different laser shapes or patterns; there are manypatterns that can be used for etching or implanting to leave conductiveareas 41 for lasers in a single mesa structure versus non-conductiveareas 42) and other structure patterns which are more rigid whileimproving bonding. Heat removal can still be accomplished by depositingmaterials with high thermal conductivity materials in the holes that areetched into the single mesa structure to produce the multiple lasers(see, e.g., holes 7005 in FIG. 7) which are closer to the junctions.Examples of additional structure patterns can include arrangements likesquares or circles on lines, etc.

FIG. 1 shows a top view of the epitaxial side of a laser chip. A singlelaser-emitting epitaxial structure 1 has an ion-implanted area, allexcept the lasing areas 2 (which are shown as disks in FIG. 1) where theion implant was masked. FIG. 1 thus represents the chip after implant,and etch. Relative to the prior design of US Pat App Pub 2011/0176567which has multiple epitaxial mesas with each mesa corresponding to asingle lasing region, the design of FIG. 1 shows a single contiguousstructure 1 that does not have multiple mesas and can instead becharacterized as a single mesa, where this single mesa includes multiplelasing regions 2. The illustration of FIG. 1 is meant to show the singlemesa structure and not the electrical contacts. This structure 1 couldbe either bottom emitting or top emitting depending on the design andreflectance on the N mirror as compared to the P mirror.

FIG. 1 shows:

-   -   1 Single Active Mesa Structure which will produce multiple        lasing points    -   2 Areas where implant is masked so that implant does not affect        epitaxial region under mask.    -   3 Etched isolation trench separating the Single Active Mesa        Structure and the Single Ground Structure    -   4 Single Ground Structure

FIG. 2 is a cutaway view of the laser chip shown by FIG. 1, where thesingle active mesa structure 1 shown by FIG. 1 is numbered as 11 in FIG.2 and where the masked implant areas 2 shown by FIG. 1 are numbered as12 in FIG. 2. FIG. 2 represents the chip after implant, and etch but notop metal. Etched region 13 isolates the single mesa structure 12 fromthe “frame” or N mesa 14 (where the single ground structure 4 from FIG.1 is shown as the frame/N mesa 14 in FIG. 2). FIG. 2 shows:

-   -   11 Implanted area of Single Active Mesa Structure isolating        multiple lasing points    -   12 Areas of the Epitaxy Masked from Implant which will produce        lasing    -   13 Etched isolation trench separating the Single Active Mesa        Structure 11 and the Single Ground Structure 14    -   14 Single Ground Structure    -   15 Quantum wells between the top P mirror and the bottom N        mirror—this is an active region where Photons are emitted    -   16 N mirror which has N contact layer or highly doped layers for        N metal electrical contact location    -   17 Laser substrate

FIG. 3 is a perspective view of the chip shown by FIGS. 1 and 2. Theimplanted region is invisible. The metal contacts are not shown. Thisillustration is to show the topology of the single mesa etch, which canbe used for either top-emitting or bottom-emitting implanted devices.The process of implant can take place before or after top metal or etch.

FIG. 4 shows a top view of the epitaxial side of an example top emittingVCSEL grid structure. The view is through a square hole in the topelectrical waveguide which is bonded by a solder process to the laserchip. The isolation etched region is hidden in this view by theelectrical waveguide. The round disks on this illustration are the holesin the top metal contact or plated metal contact region over the singlesolid mesa structure. FIG. 4 shows:

-   -   41 Hole in substrate with waveguide underneath    -   42 Holes in the top P metal so laser beams can emit through    -   43 Top of waveguide substrate    -   44 Top spreading metal on laser chip

FIG. 5 illustrates a cutaway view of the bonded electrical waveguide andlaser chip shown by FIG. 4. The signal contact for the electricalwaveguide is opened to allow the beams to propagate through the opening.Another option of this embodiment would be to have a transparent ortransmitting substrate material for the waveguide instead of a hole forthe lasers to propagate through. A transparent material such as CVD(Chemical Vapor Deposited) diamond or sapphire or glass could be anexample of that material. This figure shows the embodiment with asubstrate such as AlNi which is opaque and thus needs a hole or opening.Notice the isolation region is separating the single mesa structure fromthe single mesa ground or structure or “frame” structure which isshorted to ground.

These P and N contacts are bonded to a high speed electrical contact(see also FIG. 7B, reference numbers 751 through 754). Theground-signal-ground (GSG) electrical waveguide substrate and laserchips are aligned (see FIG. 14B) so that the negative mesa is bonded tothe negative part of the waveguide and the positive active areas whichlase are aligned to the signal pad. This alignment is defined by abonder, then heat and pressure are applied to bond the solder that hasbeen deposited on one chip or the other (see FIG. 15) The high speednature of this contact arises because the p pad is separated from the nwafer ground by plating and solder heights but mostly by removing it offthe laser substrate and placing it on an electrical waveguide substrate.The physical separations dramatically reduce capacitance, therebyincreasing the frequency response (where the frequency response islimited by the capacitance of the circuit) and yielding high frequencyoperation for the lasing grid.

In an example embodiment, for high speed operation, the surface connectsto the electrical contact at the bottom of epi design, which isaccomplished through the isolation trench (see, for example, FIG. 7Areference number 702) surrounding the single structure (see, forexample, FIG. 7A (reference number 717)). This structure is not based onmesa topology but is simply shorted to the electrical region of the Ncontact metal (see FIG. 7A (reference number 703)) through the metalplating (such as in FIG. 7C reference number 782). This is not a builtup structure or raised structure as described in US Pat App. Pub.2011/0176567 but rather uses the chip surface and the epi material to bea surface for bonding, which also makes the device much more stable androbust at bonding.

Returning to FIG. 5, the GSG Signal Pad 51 has Solder 52 electricalconnecting the P Contact Metal on the top of the Active Single MesaStructure. This allows the signal or current to be injected into themetal contact structure with holes in it for laser propagation and thenthe current flows through the non-implanted regions of the epitaxialstructures forcing current to be confined to just those defined regions.The top P mirror region has a slightly lower reflectance than the bottomN mirror allowing the light to emit from the top of the epitaxialstructure. The current flows on through the quantum wells which producethe light and heat in there junction, and into the n mirror where itproceeds to the N contact region in or near the n mirror. The currentwould then proceed up the shorted frame structure which is bonded and inelectrical contact to the ground portion of the GSG electricalwaveguide. This structure which utilizes top emitting design can be usedfor lower wavelength output designs which are lower than thetransmission cutoff of the GaAs or laser substrate material. Backemitting structures can typically only be designed for wavelengths above˜905 nm. This top emitting structure could be used with ˜850 nm or lowerto the limits of the epitaxial material set.

A single solid structure isolated from a surrounding ground with an etchwhere the single solid structure has within it ion implants; theimplants are invisible but cause the semiconductor material to benonconductive because of the crystal damage it causes. In order to makean implanted device you must mask the areas that are to be protectedfrom the damage first.

Small mesas are formed with photoresist positioned by aphotolithographic process which protects the epitaxial material fromdamage then is washed off after the implant takes place. The implanthappens in an ion implant machine which accelerates ions down a tube andyou put the wafer in front of the stream of ions.

Implanted ions can create areas of the semiconductor material that arenon-conductive. These areas of non-conductive material will force thecurrent flow through the lase areas. These non-conductive areas can alsobe created by etching a pattern similar to FIG. 1 and oxidizing thesingle structure as described below in connection with Embodiment 2.FIG. 5 shows:

-   -   50 Non Conducting Electrical Waveguide Substrate    -   51 Signal metal of electrical waveguide    -   52 Solder metal for bonding electrical waveguide to laser chip    -   53 Plated Metal shorted to P Contact Layer and electrically        connected to Signal pad of GSG electrical waveguide    -   54 P Output Mirror-Diffractive Bragg Reflector    -   55 Active Region-Quantum Wells    -   56 N Mirror where low resistance contact Layer is located    -   57 Plated Metal shorting or in electrical contact with N Contact        layer and to Ground Mesas    -   58 Solder in Electrical contact with Ground pad of electrical        high speed waveguide and in electrical contact with Grounded        Mesa structure    -   59 Area on Plated metal connected to P Metal on single mesa        structure for contacting signal pad on high speed electrical        waveguide

FIG. 24 shows a comparative view of different current flows as betweenan embodiment such as Embodiment 1 and the design taught by US Pat App.Pub. 2011/0176567. With US Pat App. Pub. 2011/0176567, each mesa issurrounded by an N metal contact area. This takes precious space or realestate on the chip as the processing to define those footstep metal ncontacts around each mesa require photolithography which limits howclosely you can space the mesas together. These limits lead to a lowerpower output per unit area than the new method. Therefore the goal ofthis old apparatus was an array for highest power and speed yet did nottake into account the vast improvement in power/area which would also bean improvement in the ultimate goal of highest Power with the highestSpeed. Also, this old method's N contact had to be large because of thestructural limitations from the old method has been removed with the newsingle structure.

With the new design described herein, a single structure has severallasers on it and only one contact around that single structure. The newstructure reduces that N metal area to the outside of the structuremaking the area per light element much smaller. This involves a large Ncontact layer calculated to carry the current load of the singlestructure. The higher current flow from the single contact can berealized through thicker metal and or thicker N contact region.

Embodiment 2 for US Pat App Pub 2017/0033535—Bottom-Emitting Implant

FIG. 6 illustrates a cutaway view of an example of a second embodiment,where the second embodiment is a bottom-emitting device with implantedregions for current confinement. The GSG electrical waveguide can beseen solder bonded to the frame-ground structure and the active singlelaser mesa structure. FIG. 6 shows:

-   -   601 Electrical Waveguide Substrate    -   602 Ground Contact and Signal Contact in that order of GSG        Electrical Waveguide    -   603 Solder-Bonding GSG Waveguide to Laser Chip    -   604 Plating Metal electrically connecting Signal pad of        Electrical Waveguide to Lasers P contact    -   605 P contact Metal    -   606 Implanted Region that has been rendered non conductive    -   607 P mirror    -   608 Active region (quantum wells)    -   609 N Mirror    -   610 Conducting Layers in N Mirror where Implant has not reached    -   611 Laser Beams Propagating through Laser Substrate    -   612 Plating Metal shorted to N contact region    -   613 Frame Area Shorted to N Contact region    -   614 Solder electrically contacting N contact on Laser to Ground        on Electrical Waveguide    -   615 Etched region isolating large single mesa from Ground Frame

Process for Embodiments 1 and 2 of US Pat App Pub 2017/0033535

An example embodiment of the process steps to create the singlestructure for embodiments 1 and 2 with implant current confinement canbe as follows.

-   -   Step 1. Use photolithography to mask areas which will not have P        Metal deposited.    -   Step 2. Deposit P Metal (typically TiPtAu ˜2000A)    -   Step 3. Photolithography lift off and wafer cleaning. O2 descum        or ash all organics off wafer.    -   Step 4. Dielectric deposit (typically SiNx ˜<1000A) used as an        etch mask    -   Step 5. Photolithographic masking using either photoresist or        metal deposited in areas to protect the epi material from being        damaged from the implant which makes the unprotected regions        non-conductive through ion bombardment. This step can be        performed later in the process but may be more difficult due to        more varied topology.

Step 6. Implant—Those skilled in the art of calculating the implantdoses will determine the dose and species of implant needed to disruptthe materials structures to the depth which will isolate the p regionsand the quantum wells from each other.

-   -   Step 7 Cleaning this photolithography is difficult due to the        implant and a deposition of metal over the photolithography such        as plating could help to make it easier to clean off the resist.    -   Step 8. Use photolithography to mask areas of dielectric which        will not be etched. This is the unique part which is the design        of the mask which creates a large isolated structure down        implants within that structure define where current cannot flow.    -   Step 9. Use plasma etch to etch through dielectric (typically Fl        based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 10. Etch pattern into Laser or Light Emitting Diode        Epitaxial material. Stop on Substrate or doped electrical        contact layer. This isolates a single large structure from the N        shorted regions around the chip    -   Step 11. Clean off mask. O2 descum or ash all organics off        wafer.    -   Step 12. Use photolithography to mask areas which will not have        N Metal deposited.    -   Step 13. Deposit N Metal (Typically GeAu/Ni/Au eutectic        composition of 80% Au/20% Ge by atomic weight. Total thickness        of AuGe layer ˜3000A or more with ˜200A Ni or more of other        diffusion barrier metal and ˜5000A of Au or more This is also        unique hear where the n metal is deposited in the n contact        etched region and also up and over the N contact structure        shorting the structure to the n-contact.    -   Step 14. Clean off mask (typically called lift off). O2 descum        or ash all organics off wafer.    -   Step 15. Dielectric deposit (typically SiNx ˜2000A) used as a        non-conductive isolation barrier    -   Step 16. Use photolithography to mask areas of dielectric which        will not be etched.    -   Step 17. Use plasma etch to etch through dielectric (typically        Fl based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 18. Clean off mask. O2 descum or ash all organics off        wafer.    -   Step 19. Use photolithography to mask areas which will not have        Plated Metal deposited.    -   Step 20. Plate areas with ˜4-5 um of Metal (typically Au) or Cu        if diffusion barrier can be deposited first.    -   Step 21. Use photolithography to mask areas which will not have        Solder deposited.    -   Step 22. Deposit Solder Metal (Typically AuSn/Au eutectic        composition of 80% Au/20% Sn by atomic weight. Total thickness        of AuSn layer ˜40000A (4 microns) or more with ˜500A Au on top        to stop any oxidation of Sn. This layer can be patterned and        deposited on the submount with electrical waveguide which is        bonded to the laser grid.

Embodiment 3 for US Pat App Pub 2017/0033535—Top-Emitting Oxidation

In a third embodiment, oxidation rather than ion implantation is used tocreate the grid of top-emitting lasing regions within the singlestructure. For example, a patterned etch can isolate conductive paths ina single structure, creating a grid of light sources. This structureexhibits multiple laser emission points from the single structure. Thelasing structure is isolated with an etched region from the groundcontact that forms the outside perimeter of the chip. This structure forEmbodiment 3 is top emitting. The conductive areas of the grid are wherelight will be emitted. The positive electrical contact can be a gridwith openings where the light is emitted.

The epitaxial material of the laser wafer can be a VCSEL design, andmost VCSELs are top emitting. The distribution of the signal using a ptype waveguide pad is typically on the laser wafer, but it should beunderstood that in an oxidated single structure embodiment that has aback emitting design, the waveguide can be on a separate substrate thatis separated from the laser n material or layer.

FIG. 7, which shows an example of Embodiment 3, illustrates an examplepattern etched into a wafer to create a single structure which allowsmultiple point lasing. The single structure of an embodiment such asthat shown by FIG. 7 is much more rigid than the thin columns made offragile crystal material as taught by US Pat App. Pub. 2011/0176567.Also, as explained with respect to an embodiment discussed above, itshould be understood that pattern of lasing areas other than that shownby FIG. 7 may be employed if desired by a practitioner.

In FIG. 7, the diagonally striped areas are preferably etched down tocreate the patterned single mesa structure in the middle of theisolation trench. All diagonally striped areas are preferably etcheddown to the bottom N electrically conductive layer 705 in FIG. 7A ortypically the larger isolation trench will be etched to the electricalcontact buried in the epitaxial design, while the smaller patterned etchareas must go deeper than the active region which isolates the lasingpoints. The patterned structure in the middle of the isolation trench isa single structure with “shaped” holes etched into it.

The holes in the large single mesa are large in this case. These holesallow the oxidation process environment to oxidize the layers in theepitaxial region. The oxide layer or layers has high aluminum contentand forms AlO₂ that grows laterally through the layer until taken out ofthe oxidation process. White areas are the surface of the chip, dottedlines are where oxidation limits current flow to unoxidized areas only.The holes in the large single mesa are large in this case. These holesallow the oxidation process environment to oxidize the layers in theepitaxial region. The oxidation layer can be formed by using a high Alcontent layer in the epi design structure which is buried below thesurface. The etched areas expose that layer which is then placed in anoxidation chamber allowing the exposed layer to oxidize inward, whereAlO₂ grows laterally through the layer until taken out of the oxidationprocess. As the length of the oxidation grows in that thin layer, itisolates or closes off the current paths with a dielectric material ofAlO₂ that is formed during the oxidation process. If the areas 7005 areetched, then the oxidation will continue to grow until only areas 7008are conductive and the area or part of the epitaxial layers whichconduct the current through that section. Electrically conductive areasallow current flow through the quantum wells (see FIG. 7A referencenumber 707) and produce lasing as the light is trapped in the cavitybetween the p mirror 709 and N mirror 706.

The oxidation length can be seen in FIG. 7 as dotted lines, all aboutthe same distance from any one exposed edge or holes in the large singlestructure that has holes formed in it. FIG. 7 also shows the largesingle mesa ground structure. Three views of cross sections areillustrated to identify where FIGS. 7A, 7B, and 7C are located. Note 7Bwhich clearly shows through this cross section that the mesa in thecenter is a single structure.

FIG. 7 shows:

-   -   7001 Frame (Single Shorted Mesa) for Electrical Contact to        Ground of Electrical Waveguide    -   7002 Etched region isolating large single mesa from Ground Frame    -   7003 Single Mesa Structure with Etched Holes    -   7004 Indents in Edges to keep edges of Single Mesa Structure        Oxidized and Non Conductive    -   7005 Etched Hole in Single Mesa Structure    -   7006 Oxidation Pattern around any Etched Edges    -   7007 Overlapped Oxidized Areas not allowing Current Flow    -   7008 Laser Aperture where Current Flows freely (same as 761 in        FIG. 7B)    -   7009 Gap in Shorted Mesa Structure to Reduce Capacitance from        Ground to Signal Pad on Electrical Waveguide

FIGS. 7A, 7A2 and 7B are side views of the example FIG. 7 embodiment.

FIG. 7A2 shows the etched holes 727 that allow the oxidation 731 toform, which confines the current into region 761 of FIG. 7B, forformation of laser beams 763.

Reference number 706 in FIG. 7A is a p mirror diffractive Braggreflector (DBR) which has one or more layers in it with very highaluminum content 708 which when exposed to hot damp conditions oxidizes708 confining the current to the areas 761 shown by FIG. 7B, which arewhere the laser beams come out. The N mirror DBR 709 has a conductivelayer 705 to take the current flow out through the N metal ohmic contact703 to the plating 782 (see FIG. 7C) which goes up and over the singleground mesa structure 718 (see FIG. 7A) to the solder 717 andelectrically connecting to the N plating on the GSG waveguide 716 andinto the N contact 715 of the waveguide.

Current confinement is a major part of a semiconductor laser. Theconcept is to force the current flow away from the edges of thestructure so there is not an issue with current flowing near roughsurface states that may exist from the etch. The current flow is alsoideally concentrated to create lasing by increasing the current densityin the material The current confinement occurs either by oxidationthrough allowing the high concentrate layers of Al to get exposed by hotdamp conditions in the oxidation process enabled by the drilled holes(e.g., this Embodiment 3), or by the implant to render all other areasnonconductive (e.g., see Embodiments 1 and 2).

FIG. 7A shows:

-   -   701 Electrical Waveguide Substrate    -   702 Etched region isolating large single mesa from Ground Frame    -   703 N Metal contact electrically contacting N contact layer    -   704 N Mirror    -   705 N Contact layer in N mirror (low resistance for ohmic        contact)    -   706 N Mirror above N contact region    -   707 Active region (quantum wells)    -   708 Oxidized Layer Closing off Current in these Regions    -   709 P mirror    -   710 Dielectric Layer    -   711 Plating on top of P contact Metal    -   712 Aperture in P Contact Metal and Plating Metal for laser beam        exit    -   713 Electrical Waveguide Substrate    -   714 Ground Contact of GSG Electrical Waveguide    -   715 Signal Contact of GSG Electrical Waveguide    -   716 Solder-Bonding GSG Waveguide to Laser Chip    -   717 Solder-Bonding GSG Waveguide to Laser Chip    -   718 Frame structure electrically connected to N contact region        of laser chip

FIG. 7A2 is a continuation of FIG. 7A above, and it further shows:

-   -   721 Ground Contact of GSG Electrical Waveguide    -   722 Plating on Ground Contact of GSG Electrical Waveguide    -   723 Solder-Bonding GSG Waveguide to Laser Chip    -   724 Signal Contact of GSG Electrical Waveguide    -   725 Solder-Bonding GSG Waveguide to Laser Chip    -   726 Plating on Signal Contact of GSG Electrical Waveguide    -   727 Etched Hole Regions in Single Mesa Substrate permits        oxidation to form Current Confinement Apertures    -   728 Plating on top of P contact Metal    -   729 Opening in Dielectric layer for electrical contact from        Plating to P Contact Layer on Laser Single Mesa Structure    -   730 Dielectric Layer    -   731 Oxidation Layer closing off current near Etched Hole Regions

FIG. 7B is a FIG. 7 cutaway view that also shows the electricalconnections and electrical waveguide that are not shown in FIG. 7. FIG.7B illustrates the cross section through the apertures created by theoxidized layer. The oxidized layer is exposed to the oxidation processthrough the holes in the single structure illustrated in FIG. 7A. Thisview also shows that the Active Mesa Structure is truly a Single MesaStructure. FIG. 7B depicts:

-   -   751 Ground Contact of GSG Electrical Waveguide    -   752 Plating on Ground Contact of GSG Electrical Waveguide    -   753 Solder-Bonding Ground of GSG Waveguide to Laser Chip    -   754 Signal Contact of GSG Electrical Waveguide    -   755 Plating on Signal Contact of GSG Electrical Waveguide    -   756 P contact Metal on Laser Chip    -   757 Opening in plating and P Contact Metal over Laser Aperture    -   758 Plating on P Contact Metal    -   759 Solder-Bonding Signal of GSG Waveguide to Laser Chip    -   760 Dielectric Layer Protecting Active Mesa Structure from N        Contact    -   761 Current Confinement Aperture formed by opening in Oxidation        Layer    -   762 Oxidation Layer Dielectric    -   763 Laser Beam Propagating through Metal Opening

FIG. 7C is a cross sectional view of the area where the P Contact orSignal of the GSG waveguide is positioned below the Laser Chip where theN Contact Frame or single structure mesa grounded to the N contact ofthe laser is above the GSG Electrical Waveguide. The large gap betweenthe Laser Ground and the P Signal Pad reduces the capacitance of thecircuit enabling higher frequency operation. FIG. 7C depicts:

-   -   780 Dielectric Layer    -   781 N Type Ohmic Contact Metal    -   782 Plating Shorting N Metal Contact to Single Ground Mesa        Structure    -   784 N Contact Layer in Epitaxial Growth    -   785 Plating Electrically Contacted to Signal Pad on Electrical        Waveguide    -   786 Metal Signal Pad Lead on GSG Electrical Waveguide    -   787 Plating on Ground Pad of GSG Electrical Waveguide    -   788 Electrical Waveguide Substrate    -   789 Gap between Conductive Signal Pad Structure and N Contact        Layer Reduces Capacitance

Process for Embodiment 3 of US Pat App Pub 2017/0033535

An example embodiment of the process steps to create the singlestructure for embodiment 3 with oxidation current confinement can be asfollows.

-   -   Step 1. Use photolithography to mask areas which will not have P        Metal deposited.    -   Step 2. Deposit P Metal (typically TiPtAu ˜2000A)    -   Step 3. Photolithography lifts off and wafer cleaning. O2 descum        or ash all organics off wafer.    -   Step 4. Dielectric deposit (typically SiNx ˜<1000A) used as an        etch mask    -   Step 5. Use photolithography to mask areas of dielectric which        will not be etched.    -   Step 6. Use plasma etch to etch through dielectric (typically Fl        based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 7. Etch pattern into Laser or Light Emitting Diode        Epitaxial material. Stop on Substrate or doped electrical        contact layer. Typically the etch is Cl based with some (high        percentage) amount of BCl3.    -   Step 8. Clean off mask. O2 descum or ash all organics off wafer.    -   Step 9. Use photolithography to mask areas which will not have N        Metal deposited.    -   Step 10. Deposit N Metal (Typically GeAu/Ni/Au eutectic        composition of 80% Au/20% Ge by atomic weight. Total thickness        of AuGe layer ˜3000A or more with ˜200A Ni or more of other        diffusion barrier metal and ˜5000A of Au or more    -   Step 11. Clean off mask (typically called lift off). O2 descum        or ash all organics off wafer.    -   Step 12. Dielectric deposit (typically SiNx ˜2000A) used as a        non-conductive isolation barrier    -   Step 13. Use photolithography to mask areas of dielectric which        will not be etched.    -   Step 14. Use plasma etch to etch through dielectric (typically        Fl based etchant) can use wet etch such as BOE (buffered oxide        etch).    -   Step 15. Clean off mask. O2 descum or ash all organics off        wafer.    -   Step 16. Use photolithography to mask areas which will not have        Plated Metal deposited.    -   Step 17. Plate areas with ˜4-5 um of Metal (typically Au) or Cu        if diffusion barrier can be deposited first.    -   Step 18. Use photolithography to mask areas which will not have        Solder deposited.    -   Step 19. Deposit Solder Metal (Typically AuSn/Au eutectic        composition of 80% Au/20% Sn by atomic weight. Total thickness        of AuSn layer ˜40,000A (4 microns) or more with ˜500A Au on top        to stop any oxidation of Sn. This layer can be patterned and        deposited on the submount with electrical waveguide which is        bonded to the laser grid.    -   Step 20. Separate laser chips from wafer with cleaving or        dicing.    -   Step 21. Design and Fabricate electrical waveguide to align to        laser chip with the design to allow high frequency operation.    -   Step 22. Align and Flip Chip Bond the laser chip to the Submount        electrical waveguide

Embodiment 4 for US Pat App Pub 2017/0033535—Bottom-Emitting Oxidation

In a fourth embodiment, an oxidated single structure with multiplelasing regions is designed as a bottom-emitter rather than a topemitter. FIG. 8 through FIG. 14C provide details about Embodiment 4 andillustrate the process which can be used to make this embodiment. Thelasing grid's light is emitted through the substrate forming a backemitter.

Light is transmissive in GaAs from wavelengths around 900 nm andgreater. If the wavelength of the light engineered in the epitaxialdesign is in the range ˜900 nm and above, the GaAs substrate transmitsthe light or is transparent to the light. If the epitaxial designincludes an N mirror that is less reflective than the P mirror, a lasersuch as a VCSEL can emit the light from the N mirror through thesubstrate. The laser beams will propagate through the material, and thesubstrate can be a platform for optical components to collimate, spread,diverge, converge or direct the light. This enables integrated opticalcircuits with extremely high bright power to be formed. The singlestructure and the ground contact can then be integrated to a high speedelectrical waveguide substrate enabling high frequency responses fromthe entire grid. A ground signal ground electrical waveguide is idealfor this high speed electrical waveguide. Another type of electricalwaveguide that may be used is a microstrip waveguide (see FIG. 15),where the signal pad is separated from the ground pad by a thindielectric layer on a substrate.

FIG. 8 is an illustration of a typical epitaxial design. Any high speeddesign can be used for VCSEL devices. FIG. 8 shows:

-   -   81 GaAs substrate    -   82 Possible position for low resistance contact layer    -   83 N Mirror layer after contact region    -   84 Low resistance N contact region    -   85 N Mirror layer after quantum wells    -   86 Quantum Well Region    -   87 Oxidation layers    -   88 P Mirror    -   89 Low resistance P Contact layer

FIG. 9 is an illustration of the first process performed, which is Pmetal deposit. This is typically a Ti/Pt/Au Layer on top of the highly Pdoped Contact Layer forming an ohmic contact. FIG. 9 shows:

-   -   91 P Metal forming Ohmic Contact after annealing process    -   92 Low Resistance P Contact Layer

FIG. 10 is a top view of the etch of the epitaxial layer down to the Ncontact layer. FIG. 10 shows:

-   -   1001 Etched Area to N Contact Layer    -   1002 Single Mesa Ground Structure    -   1003 Single Mesa Active Structure    -   1004 Etch Hole to Allow Oxidation Process to form Apertures    -   1005 Area in between all holes where there will be no oxidation        which forms conductive current confinement

FIG. 10A is a cross section view A of FIG. 10 formed before oxidationprocess, and FIG. 10A2 is a cross section view A of FIG. 10 formed afteroxidation process. FIG. 10A2 shows:

-   -   120 Oxidation completely closes off conductive path near any        etched regions that were exposed during the oxidation process.

FIG. 10B is a cross sectional view B of FIG. 10 illustrating where thecurrent confinement apertures were formed in the areas shown. This viewrepresents a section of the single mesa where no holes are penetratingthe cross section, and clearly shows that the mesa structure is a SingleMesa Structure enabling a more robust structure preferred at the bondingprocess. FIG. 10B shows:

-   -   125 Current Confinement Aperture is conductive region of Single        Mesa Structure    -   126 Oxidized Layer forming as dielectric layer near where holes        where etched    -   127 P Metal Contact Layer

FIG. 11 illustrates the dielectric layer deposited and patterned withopened via “holes” for electrical contact to the epitaxial contactlayers and sealing the semiconductor for reliability purposes. FIG. 11shows:

-   -   1101 Dielectric Layer patterned with openings or “vias”    -   1102 Opening in Dielectric Layer to P Contact Metal    -   1103 Contact Layer on Single Mesa Ground Structure

FIG. 12 shows the N metal contact after it has been deposited. FIG. 12depicts:

-   -   1201 N Contact Metal is deposited over the N Contact via hole to        make an electrical connection to the N Contact Layer.

FIG. 13 illustrates the next step of plating metal which shorts the Ncontact region to the top of the single grounded frame region, whichwill be bonded and electrically conductive to the ground pad of the GSGwaveguide. The plating also adds height to the active region reducingcapacitance and it removes heat from the active region of the devices togive the devices better performance. The plating over the active singlestructure is isolated from the N mirror and N contact region by thedielectric layer. FIG. 13 shows:

-   -   1301 Dielectric Layer preventing the Plating covering the Active        Region and extending into the holes of the single mesa structure    -   1302 Plating Covering Single Grounded Mesa Structure Shorted to        N Contact Region through N Contact Metal    -   1303 Plating Covering Active Structure and extending into the        holes of the active region where cooling can occur through a        higher thermal conductance of the plating metal    -   1304 Plated Metal extending over single frame structure for        bonding and electrically connecting to ground of GSG electrical        waveguide.

FIG. 14a illustrates solder deposited on the laser chip. This serves asthe electrical conductive bonding adhesion layer between the laser chipand the high speed electrical waveguide. FIG. 14a shows:

-   -   1401 Solder deposit

FIG. 14b illustrates the alignment of the GSG electrical waveguidebefore bonding. FIG. 14b shows:

-   -   1403 Submount for GSG Electrical High Speed Waveguide    -   1404 Ground Pad for GSG Electrical High Speed Waveguide    -   1405 Signal Pad for GSG Electrical High Speed Waveguide    -   1406 Plating Metal Deposited on Conductive areas of GSG        Electrical High Speed Waveguide

FIG. 14C illustrates the bonded laser chip to the GSG electricalwaveguide. The gap in the single grounded mesa enables high speedoperation by reducing capacitance.

Embodiment 5 for US Pat App Pub 2017/0033535

In a fifth embodiment, a microstrip or strip line electrical waveguideis used rather than the GSG waveguide, as shown by FIG. 15. Thisembodiment can also have the gap mentioned in FIG. 14c above. Thiselectrical waveguide can also be formed by a ground layer below a thindielectric with a signal lead on the top of the dielectric forming astrip line or microstrip waveguide. Openings in the dielectric can beused to contact the ground portion of the lasing grid. The width of thelines and thickness of the dielectric can be controlled to produce aspecific impedance value for circuit matching characteristics. It shouldbe understood that this technique can also be used for otherembodiments, such as Embodiment 2 or any of the embodiments discussedbelow. The view in FIG. 15 shows a cross section across the activesingle mesa structure:

-   -   151 Waveguide substrate    -   152 Metal Ground Pad across the entire waveguide    -   153 Dielectric layer separating the Ground from the signal pads    -   154 Metal Signal Pad    -   155 Metal Plating on Signal pad    -   156 Solder electrically connecting the signal pad to the single        active mesa shown here with gaps or holes etched into it.    -   157 Metal Plating on the Ground Pad    -   158 Solder electrically connecting the ground pad to the single        grounded mesa

Embodiment 6 for US Pat App Pub 2017/0033535

FIG. 16 shows a sixth embodiment. In FIG. 16 the structure is unique inthat it leaves paths for a portion of the light of each lase point to bedirected to another laser next to it in order to keep the lasing inphase. In this example the laser 161 has some of its outer modestructure reflected 162 down to the laser aperture next to it 163 whichproduces light in phase with 162. The laser which is in phase is 164 andin turn reflects from an angled reflective surface 165 back to theaperture of the laser next to it 167 which is also in phase with 164 and161 and so on. An angular and or reflective area 164 just outside of thelens or output area can divert a small portion of the light which isoverflowing from the lens or output diameter to the lasing grid adjacentto it, enabling a coherent lasing grid. Some of the light from theneighboring lasing points is injected into the lasing point which setsup the lasing points in a phase relation with each other. This allows acoherent operation of all lasing points when the structure directs someof the light from each laser to its neighbor. The reflectance, distanceand angles are very precisely calculated by one skilled in the art ofoptical modeling. Coherent operation is a benefit which has eluded laserarray operation for many years. FIG. 16 shows:

-   -   161 Large aperture laser with wide divergence only emitting a        portion of the light    -   162 A portion of the light from laser 161 is reflected to        aperture 163    -   163 Aperture of laser where reflectance conforms to the phase of        the light from 162    -   164 Large aperture laser with wide divergence only emitting a        portion of the light    -   165 Angled reflective surface on the back of the laser chip just        outside the output aperture    -   166 the reflected beam in phase with laser grid 164    -   167 Large aperture laser with wide divergence only emitting a        portion of the light

Embodiment 7 for US Pat App Pub 2017/0033535

FIG. 17 shows a seventh embodiment. In FIG. 17, the back side of thelasing grid chip has etched patterns to redirect the laser light 172 toparticularly beneficial areas. This is accomplished by diffractiveoptical elements (DOE) 171, which have the surface etched in a way thatwhen light travels through that portion, the angle of the surface andredirects 175 beams or light depending on the angle of the surface ofthe DOE. This can be used to collimate or diverge, direct or homogenizethe light. FIG. 17 does not illustrate the electrical waveguide. Themode can be controlled by the aperture sizes and characteristics of thereflective surface 173 and 174. FIG. 17 shows:

-   -   171 Redirected Laser Grid Beam from beam 172    -   172 Laser Grid Beam emitted from apertures    -   173 Contact and back of mirror for back emitting laser grid    -   174 Contact and back of mirror for back emitting laser grid    -   175 Redirected beams from laser grid

Embodiment 8 for US Pat App Pub 2017/0033535

FIG. 18 shows an eighth embodiment. In FIG. 18, a patterned diffractivegrating 184 (this is the opposite angular pattern than FIG. 17's DOE) isplaced or etched over the emission points 181 on the backside of thelaser wafer in a back emitting VCSEL design which directs the lasingpoints outward 185 from the grid. From the lens it looks like all thelasers are coming from a single point 186 behind the chip to form avirtual point source where a macro lens 187 can be used to collimate thebeam from the virtual converged source behind the chip. FIG. 18 shows:

-   -   181 Contact and back of mirror for back emitting laser grid    -   182 Aperture creating laser characteristics    -   183 Laser Beam from laser grid    -   184 Surface of Diffractive Optical Element (DOE) angled for        specific total beam grid characteristics    -   185 Redirected beams from laser grid    -   186 Converged virtual light source from all beams as seen from        lens 187    -   187 macro lens with focal point on virtual convergence point 186

Embodiment 9 for US Pat App Pub 2017/0033535

FIG. 19 shows a ninth embodiment. FIG. 19 illustrates a cross section ofthe bonded etched and oxidized Embodiment 3, except it has microlenswhich have been processed on the back of the laser chip and positionedso that one is aligned to the other and one is slightly misaligned onpurpose in order to redirect the laser beam emitted from the single mesastructure. While embodiment 3 is referenced for this arrangement, itshould be understood that any of the above back emitting embodiments anda microlens array attached to the chip or positioned above the outputgrid can be used. The microlens array can have values related to thepitch of the light conducting grid points but with a slightly differentpitch lens 74 forcing the light emitted by the lasing points to bedirected to a single area where the beams come together or seem likethey come together in front of the chip or behind the chip as in avirtual point source. If the microlens pitch is smaller than the laserpitch, it will guide the outlying lasers to a point in front of the chipor directed inward. If the microlens arrays pitch is larger than thelasers' grids' pitch, the light will be directed outward as in FIG. 19.FIG. 19 shows:

-   -   71 Laser Substrate    -   72 N Mirror    -   73 N Contact Region    -   74 MicroLens slightly offset from laser directing laser light        outward    -   75 Active region or quantum wells    -   76 Oxidized layers creating current confinement into the active        area    -   77 Etched trench creating isolation from the single ground        structure and the active single mesa structure    -   78 P Metal Contact    -   79 Hole Etched into the single mesa structure to allow oxidation        to occur    -   80 solder electrically connecting the laser chip and the High        speed electrical waveguide    -   81 Signal pad of the GSG electrical waveguide    -   82 P mirror    -   83 GSG Waveguide substrate    -   84 Plating shorting the N metal located on the N contact layer        and the single ground mesa which is in electrical contact to the        Ground Pad of the GSG electrical waveguide    -   85 Ground Pad of the GSG electrical waveguide

Embodiment 10 for US Pat App Pub 2017/0033535

FIG. 20 shows a tenth embodiment. FIG. 20 illustrates that an extendedcavity laser design can be implemented using the single grid structureby reducing the reflectivity of the N epitaxial output mirror 230 to apoint where it will not lase, then adding the reflectivity to areflective surface 231 on the back of the lasing grid which extends thecavity. This structure reduces feedback of the higher mode structure 233in the cavity, thereby forming a more fundamental mode structure for theoutput beam 235 from the grid. FIG. 20 shows:

-   -   230 Arrow pointing to incomplete N output mirror epitaxial        region.    -   231 Reflective region made of dielectrically layers with varying        indexes of refraction.    -   232 Cavity of laser beam now includes laser wafer material        extending the cavity for modal rejection.    -   233 Reflected higher order modes which are not reflected back        into the cavity    -   234 Single or lower order modes in the cavity    -   235 single or lower order modes outputted from the Extended        Cavity Device

Embodiment 11 for US Pat App Pub 2017/0033535

FIG. 21 shows an eleventh embodiment. In FIG. 21, a VCSEL structure canbe adapted to the laser grid design like the above embodiment, and theback of the lasing chip where the output reflector (deposited on top oflens shape 241) of the lasing grid emits light can have convex 241 orconcave features under the reflector to form better a focused (focusarrows 243) feedback mechanism which rejects high modes and can bedesigned to have a single mode lasing output 245 from each grid area.The overall lasing structure will then have low M2 values. A lens ormicrolens can be added to collimate the output. FIG. 21 shows:

-   -   240 Arrow pointing to incomplete N output mirror epitaxial        region.    -   241 Reflective region made of dielectrically layers with varying        indexes of refraction deposited on top of microlens structure        etched into the laser substrate or wafer    -   242 Single mode beam being reflected within the extended cavity    -   243 light from edges being directed back into the single mode        cavity from the optical element on the surface of the chip    -   244 single mode beam has more power and is more selective of the        single mode than FIG. 20's single mode beam    -   245 Output of high quality single mode beams    -   246 highly reflective epitaxial mirror

Embodiment 12 for US Pat App Pub 2017/0033535

FIG. 22 shows a twelfth embodiment. In FIG. 22, a VCSEL structure can beadapted to the laser grid design like the above embodiment except thatthe beams which exit straight out of the lens go through an externalmicrolens array which has been designed with different pitch microlensthan the laser pitches to allow redirection of the beams either to orfrom a single location like many of the above embodiments. Other formsof this technique could use a concave lens formed on the bottom of theexternal lens array which are aligned and have the same pitch as thelaser grid, while a convex laser array with a different pitch than thelaser grid is at the top. Another technique to direct beams would be touse DOEs as the top optical element instead of the convex microlenswhich are on the top of the external lens array. 252 is light reflectedback into the center of the aperture making a stronger single mode beamwhile 253 has the reflective coatings which complete the laser outputmirror cavity. 254 is the cavity and would have an antireflectivecoating deposited on the inside of the external lens cavity while alsodepositing an anti-reflective coating on the top microlens array.Another technique would be to use the flat reflective properties such asin FIG. 20 to complete the cavity mirror and have the microlens arrayoffset on the top or a DOE on top to redirect the beams. FIG. 22 shows:

-   -   250 Arrow pointing to incomplete N output mirror epitaxial        region.    -   251 Single mode beam being reflected within the extended cavity    -   252 light from edges being directed back into the center        creating strong single mode cavity from the optical element on        the surface of the chip    -   253 Reflective region made of dielectrically layers with varying        indexes of refraction deposited on top of microlens structure        etched into the laser substrate or wafer    -   254 Cavity for etched lens to not touch external lens array    -   255 External lens array transmissive material    -   256 Single Mode beam outputted by extended cavity laser    -   257 Microlens from lens array with different pitch than laser        pitch directing beams    -   258 Directed single mode beam

What is claimed is:
 1. An apparatus comprising: a laser-emittingepitaxial structure having a front and a back, wherein thelaser-emitting epitaxial structure comprises a plurality of laserregions, and wherein the laser-emitting epitaxial structure isback-emitting; a substrate on which the laser-emitting epitaxialstructure is located; a graphene lens structure located on thesubstrate, wherein the substrate and the graphene lens structure arelocated in an optical path for back-emitting laser light from thelaser-emitting epitaxial structure; and an electrical waveguideconfigured to provide current to the laser regions; wherein the graphenelens structure directs laser light from each of a plurality of the laserregions; and wherein the laser-emitting epitaxial structure comprises asingle laser-emitting epitaxial structure, each laser region of thesingle laser emitting epitaxial structure being electrically isolatedwithin the single laser emitting epitaxial structure itself relative tothe other laser regions of the single laser emitting epitaxialstructure.
 2. The apparatus of claim 1 wherein the graphene lensstructure comprises an array of graphene lenses.
 3. The apparatus ofclaim 2 wherein each of a plurality of the graphene lenses comprises aplurality of concentric graphene rings.
 4. The apparatus of claim 1further comprising: a reflective coating located on a surface of thegraphene lens structure.
 5. The apparatus of claim 1 wherein thegraphene lens structure is configured to direct light from the laserregions to emulate light originating from a single source.
 6. Theapparatus of claim 1 wherein the single laser emitting epitaxialstructure comprises a single vertical cavity surface emitting laser(VCSEL) epitaxial structure.
 7. The apparatus of claim 6 wherein thesingle VCSEL epitaxial structure does not include a plurality of mesas.8. An apparatus comprising: a laser-emitting epitaxial structure havinga front and a back, wherein the laser-emitting epitaxial structurecomprises a plurality of laser regions, and wherein the laser-emittingepitaxial structure is back-emitting; a substrate on which thelaser-emitting epitaxial structure is located; a photolithographic lensstructure located on the substrate, wherein the substrate and thephotolithographic lens structure are located in an optical path forback-emitting laser light from the laser-emitting epitaxial structure;and an electrical waveguide configured to provide current to the laserregions; wherein the photolithographic lens structure directs laserlight from each of a plurality of the laser regions; and wherein thelaser-emitting epitaxial structure comprises a single laser-emittingepitaxial structure, each laser region of the single laser emittingepitaxial structure being electrically isolated within the single laseremitting epitaxial structure itself relative to the other laser regionsof the single laser emitting epitaxial structure.
 9. The apparatus ofclaim 8 wherein the photolithographic lens structure comprises an arrayof photolithographic lenses.
 10. The apparatus of claim 8 furthercomprising: a reflective coating located on a surface of thephotolithographic structure.
 11. The apparatus of claim 8 wherein thephotolithographic lens structure is configured to direct light from thelaser regions to emulate light originating from a single source.
 12. Theapparatus of claim 8 wherein the photolithographic lens structurecomprises a masked photolithographic lens structure.
 13. A methodcomprising: depositing graphene on a back of a back-emittingmulti-conductive grid-forming laser structure, wherein the back-emittingmulti-conductive grid-forming laser structure comprises (1) an epitaxialstructure comprising a plurality of laser regions within a single mesastructure of the epitaxial structure, each laser region of the singlemesa structure being electrically isolated within the single mesastructure itself relative to the other laser regions of the single mesastructure, and (2) a substrate on which the epitaxial structure islocated; masking areas of the deposited graphene via photolithography;and forming a graphene lens structure for the back-emittingmulti-conductive grid-forming laser structure by plasma etching thedeposited graphene so that the masked areas are not plasma etched andthe graphene lens structure will direct light from each of a pluralityof the laser regions when a current is applied to the back-emittingmulti-conductive grid-forming laser structure.
 14. The method of claim13 wherein the masking step comprises masking a plurality of concentricgraphene rings that are to serve as the graphene lens structure.
 15. Themethod of claim 14 wherein the masking step comprises: controllingthickness and spacing of the graphene rings to achieve a desired opticaleffect.
 16. The method of claim 13 further comprising: depositing areflective coating over a surface of the graphene lens structure. 17.The apparatus of claim 1 wherein the substrate has a substrate front anda substrate back, wherein the laser-emitting epitaxial structure islocated on the substrate front, and wherein the graphene lens structureis located on the substrate back.
 18. The apparatus of claim 1 wherein aplurality of the laser regions are within a single mesa structure of thelaser-emitting epitaxial structure.
 19. The apparatus of claim 18further comprising: a contact layer that extends beneath the single mesastructure and is located above the substrate, wherein the contact layeris adapted to carry a current load from the electrical waveguide andspread current horizontally through the contact layer to the single mesastructure including interior laser region portions of the single mesastructure for injecting the laser regions with current to produce lasingfrom the laser regions.
 20. The apparatus of claim 8 wherein thesubstrate has a substrate front and a substrate back, wherein thelaser-emitting epitaxial structure is located on the substrate front,and wherein the photolithographic lens structure is located on thesubstrate back.
 21. The apparatus of claim 8 wherein a plurality of thelaser regions are within a single mesa structure of the laser-emittingepitaxial structure.
 22. The apparatus of claim 21 further comprising: acontact layer that extends beneath the single mesa structure and islocated above the substrate, wherein the contact layer is adapted tocarry a current load from the electrical waveguide and spread currenthorizontally through the contact layer to the single mesa structureincluding interior laser region portions of the single mesa structurefor injecting the laser regions with current to produce lasing from thelaser regions.